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Butler CL, Lucieer VL, Wotherspoon SJ, Johnson CR
Multi-decadal decline in cover of giant kelp Macrocystis pyrifera at the southern limit of its Australian range
Giant kelp forests are a key and iconic habitat that dominate many nearshore rocky coastlines in temperate waters worldwide. In Australia these ecosystems have declined dramatically over the last 50 years, particularly in Tasmania., but However, there has been no spatially comprehensive analysis to date. Butler and co-workers used satellite imagery to build a 30-year time series of giant kelp surface canopy cover around Tasmania, which showed high variability but overall collapse from > 400 ha to < 10 ha total surface cover in areas > 30 m from shore by 2015. Regression models demonstrated that water temperature is the key correlate of shifts in canopy abundance and distribution, highlighting the potential for future declines of this biodiverse habitat in areas at risk of ocean warming.